#include <stdio.h>
FILE *f=fopen("operatii.in","r");
FILE *g=fopen("operatii.out","w");
unsigned long long mx,nr,x1,x2,i,n;
int ok=1;
int main()
 {
 fscanf(f,"%lld",&n);
 fscanf(f,"%lld",&x1);
 mx=x1;
 for(i=2;i<=n;i++)
  {
  fscanf(f,"%lld",&x2);
  if(mx<x2)
   mx=x2;
  if(ok==1&&x1>x2)//e la panta
   ok=2;          //schimbam directia pe care urmarim
  if(ok==2&&x1<x2)//incepe pe alt munte
   {
   nr+=mx;
   mx=x2;
   ok=1;
   }
  x1=x2;
  }
 fprintf(g,"%lld",(nr+mx));
 fclose(f);
 fclose(g);
 return 0;
 }